Dialysis device for performing dialysis treatment

Description

Technical field

[0001] The present invention relates to a dialysis device for carrying out a dialysis treatment and a method for monitoring an operating state of a dialysis device. State of the art

[0002] Various procedures for treating a patient's blood, especially for purifying and dehydrating a patient's blood, are known.

[0003] For example, in hemodialysis, a patient's blood is purified in an extracorporeal blood circuit that includes a dialysis filter. The dialysis filter has a blood chamber, through which the patient's blood flows, and a dialysate chamber. The blood chamber and the dialysate chamber are separated by a semipermeable membrane, for example, in the form of hollow fibers whose walls form the membrane. During hemodialysis, the dialysate flows through the dialysate chamber, and the patient's blood flows through the blood chamber. Due to a concentration gradient between the dialysate and the patient's blood, substances are transported across the semipermeable membrane by diffusion.

[0004] Other blood purification methods are known, such as hemofiltration, in which substance transport through a semipermeable membrane is caused by a pressure gradient. Hemodiafiltration combines hemodialysis and hemofiltration.

[0005] The extracorporeal blood circulation essentially comprises an arterial tubing system through which blood to be purified is transported from the patient to the dialyzer, and a venous tubing system through which purified blood is returned from the dialyzer to the patient. The tubing system can also be a cassette, in which the tubes are formed, for example, by at least partially rigid fluid channels.

[0006] Both tubing systems can be connected to a pressure sensor on the dialysis unit, which determines the pressure before and after the dialysis filter, or the pressure in the arterial and venous tubing systems. This helps ensure reliable and safe dialysis. To guarantee reliable pressure monitoring, it is also necessary to regularly check the function of the safety-relevant pressure sensors. For this purpose, the system must be monitored for functionality before or during treatment, or for failure during treatment, in accordance with standard IEC 60601-2-16.

[0007] Several methods are known for verifying the function of pressure sensors. In these known methods, the pressure sensors are initially tested at zero, i.e., at atmospheric pressure. However, to verify the function of a pressure sensor with a known transfer function (in the form y = mx + t), an additional measurement point is necessary. This can be achieved by applying additional pressure to the pressure sensor, although this requires complex pneumatic tubing to decouple the test pressure of the two pressure sensors. Another possibility is to determine the second measurement point by electrically detuning the sensor signal. A disadvantage of this method, however, is that only the function of the signal path after the pressure sensor can be verified, while the function of the sensor itself, including its diaphragm, cannot be tested.

[0008] Another way to monitor the functionality of the pressure sensors is to use a second, redundant sensor for each pressure sensor. However, this significantly increases the overall costs.

[0009] Furthermore, an additional measurement point can be obtained via a so-called coupling test. In this test, for example, the venous pressure is increased by closing a clamp, and the achievement of a pressure threshold (e.g., the end of the venous scale) is verified. However, the test can only be started once a tubing system is inserted and filled with fluid, as sufficient pressure change cannot be generated by compressing air, as is the case with an empty tubing system. Moreover, performing a coupling test places high demands on the tubing system, as it must be possible to clamp the system tightly at the beginning of treatment or even during treatment preparation.

[0010] From US patent 9 925 323 B2, a system for blood monitoring in an extracorporeal blood treatment device is known, which includes a differential pressure sensor on the extracorporeal blood circuit between two sides of a membrane device.

[0011] Furthermore, US patent 6,601,432 B1 discloses a method for checking differential pressure sensors in extracorporeal blood treatment devices, wherein measurements of the respective sensors are carried out before treatment against air at a predetermined atmospheric pressure and the respective measured values ​​are compared with each other. Description of the invention

[0012] Starting from the known state of the art, it is an object of the present invention to provide a further improved dialysis device for carrying out a dialysis treatment, as well as a method for monitoring a pressure measuring device and a method for determining an operating state.

[0013] The problem is solved by a dialysis device for carrying out a dialysis treatment with the features of claim 1. Advantageous further developments are described in the dependent claims, the present description, and the figures.

[0014] Accordingly, a dialysis device for performing a dialysis treatment, comprising a fluid line system with a first section and a second section, is proposed. According to the invention, a differential pressure sensor is provided for measuring a differential pressure p diffm between a first pressure in the first section of the fluid line system and a second pressure in the second section of the fluid line system. A monitoring unit is provided, configured to determine an operating state based on the measured differential pressure p diffm. Furthermore, a control device is provided, configured to terminate and / or block the dialysis treatment according to the determined operating state, and / or a display device is provided, configured to output a message based on the determined operating state.

[0015] By providing a differential pressure sensor between the first and second sections of the fluid piping system, the differential pressure can be reliably monitored and / or the pressure sensors located on the individual sections of the fluid piping system can be tested for functionality.

[0016] Measuring the differential pressure allows for monitoring and / or functional testing of the dialysis treatment, thereby increasing patient safety. For example, if an undesirable deviation in differential pressure occurs during dialysis, a message, such as an error message, can be issued, and / or the dialysis can be stopped, and / or the start of a subsequent treatment can be blocked.

[0017] The fluid supply system can also include two or more sections from the group consisting of an arterial patient line, a venous patient line, a predialyzer dialysate line, a postdialyzer dialysate line, a substitution line, a water inlet line, and a concentrate supply line. Each of these sections can be connected to a pressure sensor to measure the pressure in the lines, and a differential pressure sensor can be provided between each of these sections to measure the pressure difference between the pressures in the first and second sections.

[0018] A dialysis machine generally enables the patient-specific removal of dissolved substances (e.g., urea, creatinine, vitamin B12, or β2-microglobulin) and, if necessary, a defined amount of water from the blood during renal replacement therapy. Such a dialysis machine can be used for hemodialysis, hemofiltration, or hemodiafiltration. Furthermore, the dialysis machine can be an ultrafiltration device, in which case water is removed from the blood without purifying it. The dialysis machine can also be an acute dialysis machine, in which the dialysate can be transferred from a bag into the dialysis circuit and from the dialyzer into a bag.

[0019] Monitoring of the operating status can be performed using blood in an extracorporeal circuit or another fluid, in particular a dialysis fluid, a filling or priming fluid in the fluid supply system. If monitoring is performed using a fluid other than blood, it can be carried out before and / or after treatment, thus ensuring that a dialysis device is functioning safely at least before and / or after treatment.

[0020] The pressure in the first section, if it refers to the arterial blood flow at the point where blood is drawn from a patient's arterial access, is also called arterial pressure. The pressure in the second section, if it refers to the venous blood flow at the point where blood is returned to the patient's venous access, is also called venous pressure. Setting and monitoring these two pressures may be necessary for various purposes. They may be important for patient safety during dialysis treatment or used to control blood flow and / or the dialysis procedure itself.

[0021] The differential pressure sensor mentioned above can be arranged between the first section and the second section.

[0022] A differential pressure sensor, as used here, refers to a pressure sensor that measures the difference between two absolute pressures, i.e., the differential pressure. The differential pressure sensor can, for example, consist of two measuring chambers hermetically separated by a diaphragm. The deflection of the diaphragm then serves as a measure of the magnitude of the differential pressure. Using this differential pressure sensor, the pressure difference pdiffm between the pressure in the first section, p1, and the pressure in the second section, p2, is measured. The following relationship exists between the pressures p1 and p2 mentioned here as examples: p diffm = p 1 − p 2

[0023] The monitoring unit records the values ​​measured by the differential pressure sensor and determines an operating condition based on this. This is done, for example, by comparing the measured values ​​with target values ​​for a differential pressure for specific operating conditions, or by observing changes in the differential pressure over time and concluding that an anomaly or an undesired operating condition occurs when an abrupt change in the differential pressure is detected.

[0024] A target value can also be a target curve; it does not necessarily have to be a constant value over time.

[0025] Operating states refer to various desired or undesired states of the dialysis process and / or the dialysis device.

[0026] A desired operating state refers, for example, to the case in which the differential pressure is approximately constant, repeats periodically, shows no drift, or one or more specific components of the pressure signal do not change over time, thus enabling effective and safe dialysis. These components can include the maximum amplitude of the pressure signal, a phase of the pressure signal, and / or a frequency component of the pressure signal, such as that which can be obtained from the periodic pressure signal using Fourier transformation.

[0027] An undesired condition occurs, for example, when the venous needle through which the purified blood is supplied to the patient is accidentally disconnected from the patient's venous access (VND, Venous Needle Disconnect), resulting in a malfunction. In this case, blood leaks uncontrollably from the blood return line, which can then no longer be supplied to the patient, potentially leading to dangerous blood loss. Because the connection between the venous needle and the patient is broken, the pressure in the blood return line drops, causing the differential pressure between the blood supply and return lines to fall. This change in differential pressure can be detected by the monitoring unit as an undesired operating condition.

[0028] Another undesirable operating condition can occur if at least one of the pressure sensors does not function correctly, and therefore the pressure measured by that pressure sensor is incorrect.

[0029] If an undesired operating condition is detected by the monitoring unit, it can immediately initiate a halt to the dialysis process to prevent patient harm and / or issue a message, such as an alarm or error message. Intervention can also consist of the device's control unit blocking the start of treatment. The action taken in response to an undesired operating condition can occur immediately after detection or at a later time. For example, it may be possible to continue an ongoing treatment and only take action after the treatment is complete.

[0030] By using the monitoring unit to determine various operating states of a dialysis machine based on a measured differential pressure between the first and second sections, a simple and reliable solution for monitoring the correct functioning of the dialysis machine is provided. Undesired operating states can be detected quickly and reliably, and intervention in the dialysis machine's operating process can be initiated immediately or at a predetermined time or event to prevent risks to the patient, such as increased blood loss.

[0031] According to the invention, a first pressure sensor for measuring a pressure in the first section and a second pressure sensor for measuring a pressure in the second section are provided, and the monitoring unit is configured to calculate a differential pressure p diffb from the first measured pressure in the first section and the second measured pressure in the second section.

[0032] According to one embodiment, a first pressure sensor is provided for determining the pressure in the blood inlet and / or a second pressure sensor for determining the pressure in the blood return. The first and / or second pressure sensor can be provided in addition to the differential pressure sensor. This allows not only the differential pressure between the pressure in the blood inlet (i.e., the pressure near the point of blood collection for dialyzing) and the pressure in the blood return (i.e., the pressure near the point where the dialyzed blood is delivered to a patient) but also the actual pressure in the blood inlet and the actual pressure in the blood return to be determined independently of the differential pressure.

[0033] The monitoring unit can detect an incorrect function of the first and / or the second pressure sensor as an operating condition.

[0034] The monitoring unit is configured to determine the operating state based on the calculated differential pressure p diffb and the measured differential pressure p diffm. To determine the operating state, the monitoring unit can be configured to calculate a difference p res between the calculated differential pressure p diffb and the measured differential pressure p diffm and to compare this difference p res with a setpoint.

[0035] According to a further embodiment, the monitoring unit is configured to determine the correct functioning of the first and / or the second pressure sensor based on the measured differential pressure and a differential pressure calculated from the measured pressure in the first section and in the second section, preferably taking into account a differential pressure p diffb calculated from the measured pressure in the first section and the measured pressure in the second section. For example, the first pressure sensor can be a pressure sensor arranged on the arterial patient line for measuring the pressure, and the second pressure sensor can be a pressure sensor arranged on the venous patient line for measuring the pressure.

[0036] To monitor the correct functioning of the pressure sensors, the absolute pressure in the first section can be measured using the first pressure sensor, and the absolute pressure in the second section using the second pressure sensor, independently of the differential pressure. A differential pressure pdiffb can be calculated from the measured pressure in the first section and the measured pressure in the second section. The monitoring unit can then be configured to compare the differential pressure pdiffm measured by the differential pressure sensor between the pressure in the first section and the pressure in the second section with the calculated differential pressure pdiffb. Subtracting these two differential pressure values ​​yields a resulting pressure pres. If the first and second pressure sensors, as well as the differential pressure sensor, are measuring correctly, the measured and calculated differential pressure values ​​are equal, resulting in a final pressure of zero.The following relationship exists between the pressures, again using the pressures p1 and p2 as examples: . p res = p 1 − p 2 − p diffm

[0037] However, since pressure measurements are usually subject to tolerances, p res can also be a non-zero value, but it is then a constant or nearly constant value resulting from the measurement tolerances of the pressure sensors.

[0038] By including a differential pressure sensor in addition to a primary and / or secondary pressure sensor, the functionality of the primary and / or secondary pressure sensor can be easily verified. This increases the reliability of the dialysis device and, consequently, patient safety. Furthermore, a complete functional check of the pressure measurement—i.e., resistance bridge, signal conditioning, ADC conversion, and signal acquisition—is unnecessary. Additionally, detuning the pressure sensors to detect offset or slope errors is not required, thus eliminating any influence of the detuning path on the measurement signal.

[0039] Another advantage is that redundant monitoring allows the use of cost-effective standard pressure sensors, eliminating the need for special intrinsically safe pressure sensors.

[0040] According to another embodiment, the fluid supply system is an extracorporeal blood circuit with a dialysis filter, wherein the first section corresponds to a blood inlet and the second section to a blood return. In the extracorporeal blood circuit of the dialysis device, the patient's blood to be purified is passed through the various elements of the dialysis device outside the patient's body. The extracorporeal blood circuit has a blood inlet (arterial patient line) and a blood return (venous patient line).

[0041] The blood inlet can be connected to an artery of the patient being treated; that is, blood to be purified is drawn from the patient into the extracorporeal circulation via the inlet. The blood to be purified can be pumped within the inlet. The return blood is connected to a vein of the patient being treated; that is, purified blood from the extracorporeal circulation returns to the patient's body via the return blood. Blood is typically drawn from and returned to a specially constructed blood vessel (shunt) or a large blood vessel of the patient. A dialysis filter is located between the inlet and return lines of the extracorporeal circulation.The blood to be purified is passed through this dialysis filter. In hemodialysis, for example, a dialysate flows countercurrently to the blood, with the dialysate flow and the blood flow separated by a semipermeable membrane. Within the dialysis filter, unwanted substances are removed from the blood through diffusion, and the blood is enriched with desired substances.

[0042] According to one embodiment, the monitoring unit is configured to detect a venous needle disconnect (VND) by means of the measured differential pressure p diffm. The term needle disconnect also includes the case where a connection in the fluid piping system becomes loose, for example, a Luer connection from the tubing system to the needle or the connection between the tubing system and the dialyzer.

[0043] The fewer pressure-influencing components are used, the more reliably a needle disconnection can be detected. This is particularly possible because the dialysis device for performing dialysis treatment in the extracorporeal blood circuit comprises only a blood pump, a dialyzer, a venous chamber with a clot collector, and a tubing system connecting these elements. Thus, no components that significantly influence the differential pressure or generate pressure fluctuations are included. Specifically, this device includes only one or more pumps for dialysate flow and one pump for blood flow, but no pump that can transfer the dialysate or substitute directly into the blood tubing system, i.e., bypassing the dialyzer membrane.

[0044] By using the differential pressure sensor and thus only one pressure transducer, there are no linearity errors and no phase differences as in the determination of needle disconnection based on p diffb, for whose calculation the signal of two pressure sensors must be used.

[0045] The problem stated above is further solved by a method for monitoring operating conditions in a dialysis device with the features of claim 6. Advantageous embodiments of the method are described in the dependent claims, the present description, and the figures.

[0046] Accordingly, a method for monitoring at least one operating state of a dialysis device comprising a fluid line system filled with a fluid other than blood, with a first section and a second section, is proposed. The method comprises the steps Measuring a differential pressure p diffm between a first pressure in the first section and a second pressure in the second section using a differential pressure sensor, determining the operating state based on the measured differential pressure p diffm, and outputting a message based on the determined operating state.

[0047] Determining a deviation of the measured differential pressure p diffm from a target value and / or determining a predetermined change in the differential pressure p diffm during dialysis treatment can indicate an undesirable operating condition.

[0048] The deviation can result from a discrepancy in a computationally processed measured differential pressure p diffm. The computational processing can, for example, involve time averaging and / or Fourier analysis for frequency-resolved evaluation and / or subtraction from a target signal waveform.

[0049] After an undesired operating condition is detected, a message is issued based on the detected condition, for example, an error message. If the differential pressure p diffm changes suddenly, for example, due to an accidentally dislodged venous needle or a defective fluid supply / drainage system, this pressure change is detected by the monitoring unit for determining the operating condition, which can then initiate an immediate stop of the dialysis treatment to prevent, for example, dangerous blood loss in the patient.

[0050] According to the invention, the method comprises the steps Measuring a pressure in the first section using a first pressure sensor, measuring a pressure in the second section using a second pressure sensor, calculating a differential pressure p diffb between the measured pressure in the first section and the measured pressure in the second section.

[0051] The method is carried out according to the invention before and / or after a treatment.

[0052] The following relationship exists between the measured pressure in the first section, the measured pressure in the second section and the calculated differential pressure p diffb - described here again using the pressures p 1 and p 2 as examples: p diffb = p 1 − p 2

[0053] According to one embodiment of the method, the operating state includes an incorrect function of the first and / or the second pressure sensor. This allows not only the pressure in the first and / or second section to be monitored, but also the correct function of the first and second pressure sensors. This prevents incorrect measurements of the pressure in the first section and / or the pressure in the second section. This, in turn, increases the overall safety of the dialysis procedure.

[0054] If the pressure in the supply line is incorrectly determined or a measurement error goes undetected, the calculation of the dialyzed blood volume may be inaccurate. Similarly, if the pressure in the return line is incorrectly determined or a measurement error goes undetected, a pressure drop caused by an accidentally disconnected venous needle or the needle becoming detached from the patient may go unnoticed. This can result in blood loss and thus pose a significant risk to the patient.

[0055] According to one embodiment of the method, after determining an incorrect function of a first pressure sensor in a first section, the pressure in the first section is determined from the measured differential pressure p diffm and the measured pressure in a second section.

[0056] According to a further preferred embodiment of the method, after identifying a malfunction of a second pressure sensor in a second section, the pressure in the second section can be determined from the measured differential pressure pdiffm and the measured pressure in a first section. If the comparison between the measured and the calculated differential pressure reveals that one of the two pressure sensors has failed, i.e., is not measuring at all, or has delivered an incorrect measurement result, the missing measurement value can be calculated using the following relationships – again described here by way of example using the pressures p1 and p2: p 1 = p 2 − p diffm p 2 = p 1 + p diffm

[0057] Because a missing measurement value can be calculated using the measured differential pressure, it is possible to reliably continue the dialysis procedure even in the event of a failure or faulty measurement of the first and / or second pressure sensor.

[0058] According to one embodiment, determining the operating state includes determining it based on the calculated differential pressure p diffb and the measured differential pressure p diffm.

[0059] The investigation may include the following steps: Calculating a resulting pressure pres from the difference between the calculated and measured differential pressure pdiffm and the measured differential pressure pdiffb, and analyzing the behavior of the pressure pres.

[0060] The analysis can be a comparison with a target value and / or an analysis of the change over time.

[0061] The resulting pressure p res is calculated as follows: p res = p diffm − p diffb

[0062] For monitoring, for example a so-called T0 monitoring, i.e. monitoring during treatment or a T1 test, i.e. testing outside of treatment, on a functioning first and / or second pressure sensor, the following relationship applies: Δ p res = p ven − p art − p diffm

[0063] In this monitoring system, a certain deviation Δp res of the resulting pressure is permitted, as each of the pressure sensors has tolerances regarding temperature drift, slope, or offset. The permissible deviation can be stored in a memory of the dialysis device, and by comparison, a processor of the dialysis device can determine whether the permissible deviation is being observed and / or exceeded.

[0064] At the latest during a subsequent T1 test, the problem detected by a monitoring unit can be displayed. The problem can then be specified using a checklist, for example, or narrowed down to the corresponding pressure sensor.

[0065] It is still possible, after a fault has been detected, to check which of the two pressure sensors has failed by briefly closing a venous clamp during treatment.

[0066] According to one embodiment of the method, if the resulting pressure deviates from the target value, an error volume is accumulated from the resulting pressure pres. If a predetermined maximum accumulated error volume is exceeded, a message is triggered and / or the dialysis treatment is aborted and / or the start of a treatment is blocked.

[0067] According to a preferred embodiment of the method, a message is sent if the resulting pressure p res deviates persistently from the setpoint when a trigger threshold is reached.

[0068] The described monitoring procedure makes it possible to monitor the pressure in the first segment, for example, the arterial pressure in the supply line, as well as the pressure in the second segment, for example, the venous pressure in the return line, and their differential pressure. This monitoring procedure thus allows for easy monitoring of the treatment progress, ensuring a correct procedure and effective treatment for the patient.

[0069] In an example not claimed by the invention, the fluid supply system can be an extracorporeal blood circuit with a dialysis filter, wherein the first section corresponds to a blood inlet and the second section to a blood return.

[0070] In another example, which is not claimed by the invention, a needle disconnection can be identified as an operating condition based on the measured differential pressure p diffm.

[0071] The method can be carried out with a previously described dialysis device, that is, all features described for the dialysis device are also disclosed for the method and vice versa. Brief description of the characters

[0072] Preferred further embodiments of the invention are explained in more detail by the following description of the figures. These show: Figure 1 shows a dialysis device with an extracorporeal blood circuit of a dialysis machine with a differential pressure sensor between a blood inlet and a blood outlet; Figure 2 shows a diagram illustrating a desired and an undesired operating state of the dialysis device. Figure 1 Figure 3 shows a dialysis device with an extracorporeal blood circuit of a dialysis machine with a first pressure sensor in a blood inlet and a second pressure sensor in a blood return and a differential pressure sensor between the blood inlet and the blood return; Figure 4 shows a diagram illustrating an exemplary pressure profile of the dialysis device. Figure 3 with correctly measuring pressure sensors, Figure 5 is a diagram showing an exemplary pressure profile of the dialysis device. Figure 3Figure 6 shows a dialysis device with an extracorporeal blood circuit of a dialysis machine, illustrating various arrangements of pressure sensors that can measure the pressure in different sections, Figure 7 shows a dialysis device with an extracorporeal blood circuit of a dialysis machine, illustrating further arrangements of the differential pressure sensor, Figure 8 shows a schematic representation of a method for monitoring an operating state of a dialysis device based on a measured differential pressure, and Figure 9 shows a schematic representation of a method for monitoring an operating state of a dialysis device based on a calculated and a measured differential pressure. Detailed description of preferred embodiments

[0073] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the different figures are designated with identical reference numerals, and repeated descriptions of these elements are sometimes omitted to avoid redundancy.

[0074] The following description details a dialysis device 1 for performing dialysis treatment and a method for monitoring at least one operating state of the dialysis device 1. The dialysis device 1, already described in general terms above, is shown in the figures in a very schematic and exemplary manner, using an extracorporeal blood circulation system 10 with at least one dialysis filter 5 and a fluid supply system 2 as an example.

[0075] In Figure 1A dialysis device 1 with a fluid supply system 2 is shown schematically, wherein the fluid supply system 2 is an extracorporeal blood circuit 10. For the following description, a blood inlet 13 corresponds to a first section 3 of the fluid supply system 2 and a blood outlet 14 to a second section 4 of the fluid supply system 2.

[0076] The dialysis device 1 further comprises a dialysis filter 5 arranged between the blood inlet 13 and the blood return 14. The blood inlet 13, also called the arterial inlet, is connected to the patient via a connection not shown here to draw blood from the patient's circulation. The blood return 14, also called the venous return, is likewise connected to the patient via a connection not shown here to return the blood treated in the dialysis filter 5 back to the patient's circulation.

[0077] The dialysis device 1 also includes a pump 9, shown here in the form of a hose pump, for pumping the blood taken from a patient through the extracorporeal blood circulation 10.

[0078] The dialysis device 1 also includes a control device 100, which is configured to control the treatment of a patient. For example, the control device 100 controls the function of the pump 9 or switches terminal 12.

[0079] Furthermore, a display device 110 is provided, by means of which the operating states of the dialysis device 1 can be displayed. In the illustrated embodiment, the display device 110 is shown in the form of a schematically depicted monitor. However, other display devices, including acoustic or haptic ones, are also conceivable.

[0080] To treat the blood of a dialysis patient using the dialysis device, the blood inlet 13 is connected to the patient's circulatory system, for example, via a cannula. The pump 9 conveys the extracted blood to the dialysis filter 5, where it is treated using known dialysis methods. For example, hemodialysis, hemofiltration, hemodiafiltration, or another known dialysis method can be performed in the dialysis filter 5. The treated blood is then returned to the patient via the blood return 14, which is also connected to the patient's circulatory system.

[0081] A differential pressure sensor 6 measures the differential pressure p diffm between the pressure p 1 in the blood inlet 13, which corresponds to arterial pressure, and the pressure p 2 in the blood return 14, which corresponds to venous pressure. The measured differential pressure p diffm is used, for example, to determine the operating status of the dialysis device 1, such as to monitor the correct function of the dialysis device 1 with regard to the function of other pressure sensors located in the Figure 1 are not shown.

[0082] In the Figure 1 A schematic representation of the dialysis device 1 is shown, in which only the differential pressure sensor 6 and a monitoring unit 11, which is set up to determine an operating state on the basis of the differential pressure p diffm measured by the differential pressure sensor 6, are provided.

[0083] Depending on the operating state determined based on the measured differential pressure p diffm, the dialysis treatment either continues in this operating state, or an error message is generated and / or the blood flow in the extracorporeal circuit is stopped. The operating state determined by the monitoring unit 11 can be communicated to the control unit 100, which then terminates the treatment or blocks the start of a treatment accordingly. Alternatively or additionally, the determined operating state can also be communicated to and displayed on a display unit 110.

[0084] If the measured differential pressure p diffm corresponds to the setpoint for a normal dialysis process, the dialysis process continues. However, if the measured differential pressure p diffm deviates from this setpoint, for example, if the venous needle returning the treated blood to the patient has slipped out or another type of needle disconnection has occurred, causing a pressure drop in the blood return 14, this is detected by the monitoring unit 11 and an error message is sent to the user and / or the extracorporeal blood circulation is immediately stopped to prevent the patient from being endangered by potentially significant blood loss.

[0085] This alarm threshold can be exceeded not only in the aforementioned deviation from a setpoint, but also in the event of a corresponding change in the differential pressure pdiffm. Therefore, an alarm can be triggered or dialysis can be stopped even if the differential pressure pdiffm changes. For example, an abrupt change in the differential pressure pdiffm may indicate an irregularity in the integrity of the connection between the extracorporeal blood circulation and the patient, potentially leading to a needle disconnection.

[0086] The evaluation of the differential pressure pdiffm over time, or the comparison of the measured differential pressure pdiffm with a target value, is performed by the monitoring unit 11, which is configured to carry out the corresponding analyses. The monitoring unit 11 can be implemented, for example, as a hardware module and / or a software module. Based on the evaluation results, the monitoring unit 11 then sends an alarm message and / or a command to terminate the dialysis treatment if an alarm condition is reached or exceeded.

[0087] Furthermore, a control unit 100 and / or a display unit 110 of the dialysis device 1 may be provided. The control unit 100 may be configured to terminate a dialysis treatment and / or block a future treatment upon receiving a message from the monitoring unit 11. The display unit 110 may be configured to output a message based on the determined operating status.

[0088] The monitoring unit 11 and / or the control unit 100 and / or the display unit 110 can also be designed as a complete unit, for example in the form of a control unit of a dialysis device with a common processor.

[0089] The monitoring device 11 can, for example, be configured to receive the signal from the differential pressure sensor 6 and can, for example, include one or more processors and memory for storing a program by means of which the monitoring steps can be executed on the processor. The monitoring device 11 can accordingly be implemented as a computer integrated into the dialysis device 1 with appropriate data lines.

[0090] The control unit 100 can also consist of a system where only the program code for the control differs from the program code of the monitoring unit 11, but at least partially uses the same hardware, for example, a common processor. The control unit 100 and the monitoring unit 11 can also, for example, exist in different software modules.

[0091] The control unit 100 can be programmed to prevent or stop a blood pump from starting, thus blocking or stopping a treatment with the dialysis device 1. Blocking can also consist of preventing a user action from being displayed as executable. For example, an operating button on the machine or on a screen of the machine may be inactive.

[0092] The display device 110 can be in the form of a screen, for example in the form of a touch screen and / or a loudspeaker for outputting acoustic signals and / or an optical signal generator such as a lamp.

[0093] In Figure 2 A diagram is shown which illustrates a desired operating state A and an undesired operating state B of the dialysis device 1. Figure 1This diagram schematically depicts the pressure p [mmHg] of the measured differential pressure p diffm and the pressure p1 in the blood inlet 13 and the pressure p2 in the blood outlet 14 over time t [s]. The values ​​of the pressure p1 in the blood inlet 13 and the pressure p2 in the blood outlet 14 are shown schematically for illustrative purposes only and are determined by the dialysis device 1. Figure 1 not necessarily measured directly - in the Figure 1 Accordingly, no pressure measuring devices for the pressures in the blood inlet 13 and in the blood return 14 are shown.

[0094] For the sake of simplicity, the pressures shown are represented linearly, which may, for example, correspond to an average pressure. The actual pressures can, of course, fluctuate periodically with the heartbeat and the pumping action of pump 9. In the desired operating state A, the pressure p1 in the blood inlet 13 and the pressure p2 in the blood outlet 14 remain essentially constant, at least with respect to their average values. Therefore, the differential pressure pdiffm measured by the differential pressure sensor 6 also remains essentially constant. In such a case, the monitoring unit 11 does not generate an error alarm and / or a command to terminate the treatment.

[0095] Undesired operating condition B schematically illustrates the fault situation in which the venous needle, which is intended to supply the patient with purified blood, has become detached from the patient's vein (VND, Venous Needle Disconnect). If there is no longer a connection between the needle, i.e., the outlet of the blood return line 14, and the patient's vein, a (slight) pressure drop p₂ occurs in the blood return line 14. Due to this pressure drop, the differential pressure pₘdiffm measured by the differential pressure sensor also changes. The monitoring unit 11 detects this change in the pressure drop of the differential pressure pₘdiffm and sends an error message and / or initiates an immediate stop of the dialysis process or the pump 9.

[0096] In Figure 3The diagram schematically shows a dialysis device 1 with an extracorporeal blood circuit 10, comprising a first pressure sensor 7 arranged in a first section 3, located here in a blood inlet 13, and a second pressure sensor 8 arranged in a second section 4, located here in a blood return 14. A differential pressure sensor 6 is shown between the first section 3 and the second section 4. The dialysis device also includes a monitoring unit 11, which is configured to determine the correct functioning of the first and / or the second pressure sensor 7, 8 and thus ascertains the operating status.

[0097] By means of the in Figure 3 With the dialysis device 1 shown, it is therefore possible to check the function of the first and / or the second pressure sensor 7,8 as an operating state.

[0098] The dialysis device 1 again includes a pump 9 for pumping the blood drawn from a patient and a dialysis filter 5. To treat the blood of a dialysis patient using the dialysis device 1, the blood inlet 13 is connected to a vein of the patient. The blood drawn from the patient is pumped by the pump 9 to the dialysis filter 5, in which the patient's blood is purified using a known dialysis process, for example, hemodialysis, hemofiltration, hemodiafiltration, or another dialysis method.

[0099] The purified blood is then returned to the patient via the blood return line 14, which is also connected to this vein. The differential pressure pdiffm between the pressure p1 in the blood supply line 13 (i.e., the first section 3 of the fluid supply system 2) and the pressure p2 in the blood return line 14 (i.e., the second section 4 of the fluid supply system 2) is measured by the differential pressure sensor 6. Additionally, the pressure p1 in the first section 3 is measured by the first pressure sensor 7, and the pressure p2 in the second section 4 is measured by a second pressure sensor 8.

[0100] If the measured differential pressure p diffm is considered in isolation, it can be – as already mentioned – Figure 1 described - a statement is made about the operating state of the dialysis device 1.

[0101] To monitor the first and / or the second pressure sensor 7, 8, a differential pressure pdiffb is calculated in the monitoring unit 11 using the measured pressure p1 in the first section 3 and the measured pressure p2 in the second section 4. Then, the differential pressure pdiffm measured by the differential pressure sensor 6 and the calculated differential pressure pdiffb are compared, for example, by subtracting them. The comparison between the measured differential pressure pdiffm and the calculated differential pressure pdiffb yields a resulting pressure pres.

[0102] In the event that both pressure sensors 7, 8 function correctly, i.e., that pressure sensor 7 correctly measures the pressure p 1 in the first section 3 and pressure sensor 8 correctly measures the pressure p 2 in the second section 4, the measured differential pressure and the calculated differential pressure will match, i.e., the resulting pressure p res will be zero or at least constant over time.

[0103] In the event that both or one of the two pressure sensors 7, 8 malfunction, i.e., that pressure sensor 7 does not correctly measure the pressure p1 in the first section 3 and / or pressure sensor 8 does not correctly measure the pressure p2 in the second section 4, the measured differential pressure pdiffm and the calculated differential pressure pdiffb will not match, i.e., the resulting pressure pres will be non-zero or variable over time. The evaluation of the resulting pressure pres, i.e., the calculation of the resulting pressure pres from the measured differential pressure pdiffm and the calculated differential pressure pdiffb and the comparison with a setpoint (e.g., zero), is performed by the monitoring unit 11. If a deviation of the resulting pressure pres from the setpoint is detected, an error message is generated and / or the extracorporeal blood circulation 10 is stopped.

[0104] An example pressure curve for the case where both pressure sensors 7 and 8 measure correctly is shown in the schematic diagram in Figure 4 shown. The diagram in Figure 4 The graph shows the measured pressures p₁, p₂, and pₘdm, as well as the calculated pressures pₘdb and pₘres. The pressure profile p [mmHg] over time t [s] is plotted for each value. As can be seen from the graph, the calculated differential pressure pₘdb and the measured differential pressure pₘdm are identical; that is, the difference between the calculated differential pressure pₘdb and the measured differential pressure pₘdm is zero. In this case, no error message is generated by monitoring unit 11, and the dialysis procedure continues.

[0105] In a case where pressure sensors 6, 7, 8 with tolerances are used, a difference will exist between the measured differential pressure pdiffm, which is subject to tolerances, and the differential pressure pdiffb, which is also subject to tolerances since it is calculated from two measured values ​​p1, p2 with tolerances. Therefore, the resulting pressure is not zero, but is essentially constant over time. The analysis by the monitoring unit 11 can take this into account and still consider a deviation of the resulting pressure from the zero line within a predefined tolerance range as not being a fault.

[0106] In Figure 5 A schematic diagram is shown, illustrating an example pressure curve for the case where the second pressure sensor 8, which is supposed to measure the pressure p2 in the blood return, does not measure correctly. The diagram in Figure 5The graph shows the measured pressures p1, p2, pdiffm and the calculated pressures pdiffb and pres. The pressure profile p [mmHg] is plotted against the time t [s].

[0107] As can be seen from the diagram, the calculated differential pressure p diffb and the measured differential pressure p diffm do not match; that is, the difference between the calculated differential pressure p diffb and the measured differential pressure p diffm is not zero, and the deviation exceeds a predefined tolerance. The monitoring unit 11 detects this deviation of the differential pressure p diffm from the setpoint and sends an error message or stops the extracorporeal blood circulation 10.

[0108] In the Figure 6 and 7Each schematically depicts a dialysis device 1 with an extracorporeal blood circuit 10, a first pressure sensor 7 in a first section 3 corresponding to the blood inlet 13, and a second pressure sensor 8 in a second section 4 corresponding to the blood return 14. As described above, differential pressure sensors can be arranged between different sections of the fluid piping system 2, and the function of the pressure sensors arranged at these sections can be monitored accordingly by means of the respective differential pressure sensor.

[0109] In Figure 6 The following are shown as examples: various sections of the liquid piping system 2 and pressure sensors measuring the pressure in these sections.

[0110] Pressure sensors are shown, for example, in the form of a pressure sensor 7 for determining a pressure p1 between an arterial end of the arterial blood supply 13 and the blood pump 9, a pressure sensor 8 for determining a pressure p2 between a venous end of the venous blood return 13 and the dialyzer or dialysis filter 5, a pressure sensor 7a for determining a pressure p3 in a section 20 of the fluid supply system 2 between the blood pump 9 and the dialyzer 5, a pressure sensor 7b for determining a pressure p4 in a dialysate line downstream of the dialyzer 5, and / or a pressure sensor 7c for determining a pressure p5 in the dialysate line upstream of the dialyzer 5. The dialyzer 5, with its supply and return lines, forms a dialyze fluid circuit 50.

[0111] In Figure 7Various sections of the fluid piping system 2 and corresponding differential pressure sensors for measuring the differential pressure between these sections are shown.

[0112] This figure illustrates various possible arrangements of differential pressure sensors 6a to 6c. The differential pressure sensors 6a to 6c can be located in sections of areas with different pressure regimes. The dialysis device 1, which is located in the Figure 6 and 7 As shown, each of the pressure sensors 7a to 7c and the differential pressure sensors 6a to 6c has its own or combined monitoring units, which are not shown for clarity.

[0113] In the sections between which a differential pressure sensor 6a to 6c is arranged, an element may be located which, through its resistance, influences the pressure transmission from a first section 3, for example a blood inlet 13, to a second section 4, for example a blood return 14. This element may be, for example, a pump, in particular a peristaltic pump, hollow fibers of a dialysis membrane, a dialysis membrane, a flow restrictor, a valve, a chamber that is partially filled during operation, or a similar element. This element may also be a pressure-generating element, for example a pump, in which the pressure fluctuations before and after this element are in phase with each other.

[0114] If these pressure-changing elements are passive and the pressures in sections 3 and 4 are generated by completely different pressure generators, for example, two independently operating pumps, it may be necessary to average the signal over a predetermined period to average these independent fluctuations of the pressure signals to a stable value. This may also be the case, for example, if the first section is in the extracorporeal blood circuit 10 and the second section is on the side of the dialysis fluid circuit 50.

[0115] The dialysis device 1 can also have a differential pressure sensor 6a to 6c that is connected to more than two sections 3, 4. Furthermore, a controller (not shown) can be provided that is configured to connect exactly two sections 3, 4 at a time via the differential pressure sensor 6a to 6c and to perform one of the described monitoring procedures for these sections 3, 4 and / or the pressure sensors 7a to 7c connected to these sections.

[0116] A storage unit of the dialysis device 1 can store how long or over how many measured values ​​the averaging of the pressure signals must take place, depending on the respective connected sections or pressure sensors.

[0117] Another parameter stored in the memory unit, determining the duration or number of measurements for averaging, can also be the speed at which the dialysis device's pumps transport the fluid through the respective sections 3 and 4. This can be represented, for example, by a table or an equation stored in the memory unit. If the pressures in the individual sections 3 and 4 are measured by independent pressure sensors, a program running in a processor of the dialysis device 1 can average the pressure profiles until the fluctuations in the pressure profiles fall below a predefined limit stored in memory.

[0118] In Figure 8Figure 1 shows a schematic representation of a method for monitoring the operating state of a dialysis device. The method is preferably carried out with a previously described dialysis device 1, which comprises a fluid supply system 2 with a first section 3 and a second section 4.

[0119] In a first step S1 of the described procedure, a differential pressure p diffm between a first pressure p 1 in section 3 and a second pressure p 2 in the second section 4 is measured using a differential pressure sensor 6.

[0120] In a second step S2, an operating state is determined based on the measured differential pressure p diffm.

[0121] If an undesired operating condition is detected in step S2, for example, if the venous needle through which the purified blood is administered to the patient is accidentally disconnected from the patient's venous access (VND, Venous Needle Disconnect), a message is issued, for example, via a display unit 110. This message alerts the user that an undesired operating condition exists, allowing the user to immediately initiate appropriate measures.

[0122] If the determination of the operating state in step S2 shows that a desired operating state exists, for example in the case where the differential pressure is approximately constant and dialysis can therefore be carried out effectively and safely, the treatment is continued.

[0123] In Figure 9Figure 1 shows a schematic representation of a method for monitoring the operating state of a dialysis device 1 based on a calculated differential pressure p diffb and a measured differential pressure p diffm.

[0124] In step S4, a first pressure p1 is measured in a first section 3. In step S5, a second pressure p2 is measured in a second section 4. Using the measured first pressure p1 and the measured second pressure p2, the differential pressure pdiffb is calculated in step S6.

[0125] In parallel, afterwards or also before, a differential pressure p diffm between the first pressure p 1 in section 3 and the second pressure p 2 in the second section 4 is measured in a step S1 using a differential pressure sensor 6.

[0126] Using the calculated differential pressure p diffb and the measured differential pressure p diffm, a resulting pressure p res is calculated in step S8.

[0127] Based on the calculated resulting pressure pres, the operating state of the dialysis device 1 is determined in step S7, and an analysis is performed in step S9. Where applicable, all individual features shown in the exemplary embodiments can be combined and / or exchanged without departing from the scope of the invention as defined in the claims. Reference symbol list

[0128] 1 Dialysis device 2 Fluid line system 3 First section 4 Second section 5 Dialysis filter 6 Differential pressure sensor 6a - 6c Differential pressure sensor 7 First pressure sensor 7a - 7c Pressure sensor 8 Second pressure sensor 9 Pump 10 Extracorporeal blood circuit 11 Monitoring unit for determining an operating state 12 Clamp 13 Blood inlet 14 Blood outlet 100 Control device 110 Display device p 1 First pressure p 2 Second pressure p art Arterial pressure p ven Venous pressure p diffm Measured differential pressure p diffb Calculated differential pressure p res Resultant differential pressure A Desired operating state B Undesired operating state S1 Measuring a differential pressure p diffm S2 Determining the operating state S3 Terminating a dialysis treatment S4 Measuring the pressure p 1 S5 Measuring the pressure p 2 S6 Calculating the differential pressure p diffb S7 Determining the operating state S8 Calculating a resulting pressure p res S9 Analysis

Claims

1. Dialysis device (1) for carrying out a dialysis treatment, comprising a liquid line system (2) which comprises a first section (3) and a second section (4), wherein a differential pressure sensor (6) is provided for measuring a differential pressure pdiffm between a first pressure (p1) in the first section (3) of the liquid line system (2) and a second pressure (p2) in the second section (4) of the liquid line system (2), wherein a monitoring unit (11) is provided which is configured to determine an operating state on the basis of the measured differential pressure pdiffm, and wherein a control device (100) is provided which is configured to abort and / or to block the dialysis treatment in accordance with the determined operating state, and / or in that a display device (110) is provided which is configured to output a message on the basis of the determined operating state, characterized in that a first pressure sensor (7) is provided for measuring a pressure (p1) in the first section (3) and a second pressure sensor (8) is provided for measuring a pressure (p2) in the second section (4), and in that the monitoring unit (11) is configured to calculate a differential pressure pdiffb from the first measured pressure (p1) in the first section (3) and the second measured pressure (p2) in the second section (4), and wherein the monitoring unit (11) is configured to determine the operating state on the basis of the calculated differential pressure pdiffb and the measured differential pressure pdiffm.

2. Dialysis device (1) according to claim 1, characterized in that the operating state comprises an incorrect function of the first and / or of the second pressure sensor (6, 7, 8).

3. Dialysis device (1) according to claim 1 or 2, characterized in that, in order to determine the operating state, the monitoring unit (11) is configured to determine a difference pres between the calculated differential pressure pdiffb and the measured differential pressure pdiffm and to compare the calculated difference pres with a setpoint value.

4. Dialysis device (1) according to one of claims 1 to 3, characterized in that the first section (3) and the second section (4) of the liquid line system (2) have parts of an extracorporeal blood circuit (10) with a dialysis filter (5), wherein the first section (3) corresponds to a blood inflow (13) and the second section (4) corresponds to a blood return flow (14).

5. Dialysis device (1) according to claim 4, characterized in that the monitoring unit (11) is configured to detect a needle disconnection as an operating state on the basis of the measured differential pressure pdiffm and / or a change in the measured differential pressure pdiffm.

6. Method for monitoring an operating state of a dialysis device (1) which comprises a liquid line system (2) filled with a liquid other than blood with a first section (3) and a second section (4), comprising the steps of - measuring (S1) a differential pressure pdiffm between a first pressure (p1) in the first section (3) and a second pressure (p2) in the second section (4) by means of a differential pressure sensor (6), - determining (S2) the operating state on the basis of the measured differential pressure pdiffm, and - outputting a message on the basis of the determined operating state, characterized in that the method comprises the steps of - measuring (S4) a pressure (p1) in the first section (3) by means of a first pressure sensor (7), - measuring (S5) a pressure (p2) in the second section (4) by means of a second pressure sensor (8), - calculating (S6) a differential pressure pdiffb between the measured pressure (p1) in the first section (3) and the measured pressure (p2) in the second section (4), - determining (S7) the operating state on the basis of the calculated differential pressure pdiffb and the measured differential pressure pdiffm, wherein the method is carried out before and / or after a treatment.

7. Method according to claim 6, characterized in that the operating state comprises an incorrect function of the first and / or of the second pressure sensor (7, 8).

8. Method according to one of claims 6 or 7, characterized in that the determination of the operating state comprises the following steps: - calculating (S8) a resulting pressure pres from the difference between the calculated differential pressure pdiffb and the measured differential pressure pdiffm, and - analyzing (S9) the behavior of the pressure pres.

9. Method according to claim 8, characterized in that the analysis (S9) is a comparison with a setpoint value and / or an analysis of the change over time.

10. Method according to claim 9, characterized in that, in the event of a deviation of the resulting pressure pres from the setpoint value, an error volume is accumulated from the resulting pressure pres and the message is issued when a predefined maximum error volume is exceeded.

11. Method according to one of claims 9 or 10, characterized in that, in the event of a sustained deviation of the resulting pressure pres from the setpoint value, the message is issued when a trigger threshold is reached.

12. Method according to one of claims 7 to 11, characterized in that, after determination of an incorrect function of a first pressure sensor (7) in a first section (3), the pressure (p1) in the first section (3) is determined from the measured differential pressure pdiffm and the measured pressure (p2) in a second section (4).